Infrared thermal run-away detection for battery packs

ABSTRACT

Systems and methods for identifying thermal run-away events in a battery pack can include using infrared sensors to measure infrared radiation emitted by and reflected by subsets of the battery cells arrayed in a battery pack. Each infrared sensor can generate temperature data based on the received infrared radiation, which includes reflected infrared radiation for several and potentially many individual battery cells aligned in rows or columns within the battery pack. Each infrared sensor can sense the beginning of a thermal run-away event by sensing when an individual battery cell in the array has a temperature exceeding a threshold, and can generate a signal indicative of a thermal run-away event based on the detected excessive temperature.

BACKGROUND

Electric vehicles have been developed for a wide variety of personal andindustrial tasks including personal transportation, commercialtransportation, entertainment, and industrial applications. One exampleof an electric vehicle that has become commonplace is theremote-controlled or semi-autonomous unmanned aerial vehicle (UAV). UAVsmay have significant applications in personal use (e.g., forentertainment) but may also have significant commercial applications asplatforms for videography, for moving inventory in supply chainfacilities, or even for carrying parcels in commercial delivery.Increasingly, personal and commercial vehicles also include electric orhybrid electric drive trains, and or increasingly offered withautonomous features. As operational requirements of electric vehicleshave increased, power requirements have also increased, leading to aneed for reliable, high-density power supplies. Conventionalhigh-density power supplies contain numerous individual cells, which arespaced apart to manage heat and to prevent battery cells fromoverheating or entering thermal run-away conditions. However, as thedemand for power density increases, new solutions for temperaturemanagement are needed.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments in accordance with the present disclosure will bedescribed with reference to the drawings, in which:

FIG. 1 illustrates an example system for detecting thermal run-away inthe battery pack of an electric or hybrid electric vehicle, inaccordance with various embodiments;

FIG. 2 illustrates an example system for detecting thermal run-away inthe battery pack of an unmanned aerial vehicle (UAV), in accordance withembodiments;

FIG. 3 illustrates an example system for detecting thermal run-away inthe battery pack of an autonomous or semiautonomous electric vehicle, inaccordance with embodiments;

FIG. 4 illustrates an example of a battery control system for detectingthermal run-away in a battery pack using infrared sensors, in accordancewith embodiments;

FIG. 5 illustrates a second example of a battery control system fordetecting thermal run-away the battery pack using infrared sensorsarranged in multiple directions, in accordance with embodiments;

FIG. 6 illustrates an example battery control system for detectingthermal run-away in a battery pack using thermistor-based sensingcircuits, in accordance with embodiments;

FIG. 7 illustrates a second example of a battery control system fordetecting thermal run-away in a battery pack using a thermistor basedsensing mesh, in accordance with embodiments;

FIG. 8 illustrates a first example of a thermistor based sensing circuithaving thermistors arranged in series, in accordance with embodiments;

FIG. 9 illustrates a second example of a thermistor based sensingcircuit having thermistors arranged in parallel, in accordance withembodiments;

FIG. 10 illustrates an example of a thermistor based sensing mesh, inaccordance with embodiments;

FIG. 11 illustrates an example of a thermistor based sensing circuithaving sensing nodes that include thermistors in parallel with nonlineardiodes, in accordance with embodiments;

FIG. 12 is a process flow diagram illustrating a method of sensingthermal run-away in a battery pack using an infrared sensor, inaccordance with embodiments;

FIG. 13 is a process flow diagram illustrating a method of sensing andlocating thermal run-away in a battery pack using infrared sensors, inaccordance with embodiments;

FIG. 14 is a process flow diagram illustrating a method of sensingthermal run-away in a battery pack using a thermistor based sensingcircuit, in accordance with embodiments;

FIG. 15 is a process flow diagram illustrating a method of sensing andlocating thermal run-away in a battery pack using thermistor basedsensing circuits, in accordance with embodiments;

FIG. 16 is a process flow diagram illustrating a method of sensingthermal run-away in a battery pack and managing power output to a load,in accordance with embodiments;

FIG. 17 is a process flow diagram illustrating a method of sensingthermal run-away in a battery pack and managing safe shutdown of a UAV,in accordance with embodiments; and

FIG. 18 is a process flow diagram illustrating a method of sensingthermal run-away in a battery pack and managing safe shutdown of anautonomous or semiautonomous vehicle, in accordance with embodiments.

DETAILED DESCRIPTION

In the following description, various embodiments will be described. Forpurposes of explanation, specific configurations and details are setforth in order to provide a thorough understanding of the embodiments.However, it will also be apparent to one skilled in the art that theembodiments may be practiced without the specific details. Furthermore,well-known features may be omitted or simplified in order not to obscurethe embodiment being described.

The internal structure of a high-density battery includes a cavitycontaining an array of individual battery cells. The cells generate heatwhile charging or discharging, which, uncontrolled, can lead to thermalrun-away events in which thermal overload causes uncontrolled discharge(e.g., a short circuit) that further increases temperature, leading tobattery failure. Thermal run-away events are prevented by increasing theamount of spacing between individual battery cells or by shutting downthe process using the battery when thermal run-away is detected.However, increasing the amount of spacing decreases the cell density andtherefore the power density of the battery, and shutting down a batterysuddenly can be dangerous in the context of electric vehicles, automatedvehicles, or UAVs. For example, sudden battery failure of a UAV whenflying under load or when flying above people can pose a risk of anunexpected crash. Battery packs for vehicles, UAVs, or otherhigh-performance devices may be required to output 10's of kWs to 100'sof kWs, and may include arrays of hundreds or thousands of individualbattery cells. Each one of these individual battery cells has thepotential to enter thermal run-away in response to, e.g., manufacturingdefects, degradation as the cells age, local shorts caused by damage orabuse of the battery pack, or variability in the way that the cells areused or cooled during use.

Embodiments herein are directed to systems and methods for sensingprecursor conditions to a thermal run-away event at the level ofindividual battery cells in a battery, in order to anticipate thermalrun-away with sufficient time to prevent sudden battery failure, or inorder to detect and isolate thermal run-away to a particular problemcell in order to minimize damage to the battery as a whole.Specifically, embodiments herein are directed to a battery structure,and to methods of detecting the beginnings of thermal run-away, atindividual battery cells in a high density battery by sensingtemperature change within the array of battery cells.

According to at least some embodiments, temperature changes inindividual battery cells of an array of battery cells can be detectedusing infrared sensors positioned within the array of battery cells inorder to receive reflected infrared radiation from within the array tofacilitate the detection of thermal run-away at a single battery cell,before the temperature of the battery as a whole has changed enough fordetection. These methods are advantageous over conventional temperaturemonitoring for the additional reason that, whereas the temperature ofthe battery as a whole may change routinely as the battery is placedunder load or charged, the temperature of the individual battery cellsshould change in tandem with each other. Therefore, detecting suddentemperature spikes at the level of individual battery cells can greatlyimprove the accuracy of detecting a thermal run-away event.

According to various other embodiments, temperature changes inindividual battery cells of an array of battery cells can be detectedusing a string or a mesh arrangement of temperature sensors that can berouted through the array of battery cells and connected with some or allof the battery cells. The string or mesh of temperature sensors candetect sudden changes in temperature caused by isolated temperaturespikes in individual battery cells before the temperature of the batteryas a whole has noticeably risen.

FIG. 1 is a simplified block diagram illustrating an example system 100for detecting thermal run-away in the battery pack of an electric orhybrid electric vehicle 101, in accordance with various embodiments. Theelectric or hybrid electric vehicle 101 includes a power supply 105 thatis operable to supply electrical power to the electrical load or motor103 under the control of the vehicle controller 107. The vehiclecontroller 107 can include one or more processors 109 and a memorydevice 111 containing executable instructions that, when executed by theprocessor, configure the vehicle controller to manage an output of thepower supply 105 to the electrical load or motor 103, manage returnpower that may be supply by the electrical motor (e.g., in the case ofregenerative braking) to the power supply. According to someembodiments, e.g. where the electric or hybrid electric vehicle isautonomous or semiautonomous, the vehicle controller 107 may be furtherconfigured to take control of the vehicle including the management ofacceleration and braking, steering, and navigation. The electrical loador motor 103 can include any suitable electric motor for use in thedrivetrain of electric or hybrid electric vehicle such as an AC electricmotor or a DC electric motor. The electrical load 103 may furtherinclude other types of power draws, including computer systems on boardthe electric or hybrid electric vehicle 101, entertainment devices, airconditioning, heating, or any other suitable power draw. The vehiclecontroller 107 may be further connected with the user input/outputdevice 112 that can take commands from an operator of the electric orhybrid electric vehicle 101, or can relay information from the controlsystem 100 for display to the operator. The user input/output device 112can include any suitable display screen, keyboard, touchpad, voicerecognition system or software, or other suitable control system orfeedback system.

According to various embodiments, the power supply 105 can include abattery pack 120 and a battery pack controller 127 that manages outputfrom the battery pack. The battery pack 120 includes an array of batterycells 121. The battery cells 121 are typically elongate battery cellsthat are arranged in a closely packed array with air-filled spacebetween the battery cells for exhausting heat and thermally isolatingthe battery cells from each other. According to various embodiments, thebattery cells 121 are cylindrical battery cells that are sandwichedbetween substantially planar enclosure elements. According to someembodiments, the array of battery cells 121 are lithium ion batterycells. The battery pack 120 can be configured to provide a substantialrange of different power outputs, depending on the type and number ofbattery cells 121 included in the array battery cells. The number ofbattery cells 121 contained in the battery pack 120 can vary fromhundreds of individual battery cells to potentially thousands ofindividual battery cells, and provide power outputs ranging from tens ofkilowatts of power up to hundreds of kilowatts of power.

The battery pack controller 127 can include additional processingability via an onboard processor 111 and a memory device 113 containingexecutable instructions that manage the operation of the battery packcontroller. According to some embodiments, the battery pack controller127 can be a printed circuit board (PCB) that is lightweight and lowvoltage, that interfaces with the battery cells 121 to monitor voltageoutput and capacity, and interfaces with sensors 125 within the batterypack 122 detects thermal variation and for early detection of thermalrun-away events.

The battery pack 120 includes sensors 125 that are positioned adjacentthe battery cells 121 or connected with the battery cells to sensetemperature variations of the individual battery cells within thebattery pack. According to various embodiments, the sensors 125 caninclude infrared sensors that monitor an interior of the battery packfor infrared radiation indicative of temperatures above a thresholdtemperature. According to various other embodiments, the sensors 125 caninclude sensing circuits made up of thermistors that are attached togroups or subsets of the battery cells 121 in order to detect theoccurrence of thermal run-away events in the battery cells beforethermal failure has spread to the entire battery pack 120.

The principal components described above with reference to the exampleelectric or hybrid electric vehicle 101 can apply to a variety ofelectric vehicles and unmanned aerial vehicles described below.Variations of the battery control systems for detecting thermal run-awayin preventing damage due to thermal run-away events are described belowwith references to FIGS. 2 and 3, which illustrate, respectively, acontrol system 200 for a battery powered UAV 201, and a control system300 for a battery powered autonomous or semiautonomous vehicle 301. Inaddition, it will be understood that the components and principlesdescribed herein apply to a variety of vehicles that utilize electricpower, including trains, ships, robotic devices, robotic drive units,and other suitable electronic devices.

FIG. 2 illustrates an example system 200 for detecting thermal run-awayin the battery pack 220 of an unmanned aerial vehicle (UAV) 201, inaccordance with embodiments. The UAV 201 includes a power supply 205that is operable to supply electrical power to the electric motors 203under the control of the UAV controller 207. According to someembodiments, the UAV controller 207 may be further configured to takecontrol of the vehicle including the management of acceleration,altitude, pitch, yaw, and any additional functions of the UAV such aslanding, taking off, carrying items and releasing items, capturingvideo, or any other suitable function of a UAV. The electrical motors203 can include any suitable electric motor for use in powering rotors228 via rotor shafts 229 in order to propel the UAV 201, such as an ACelectric motor or a DC electric motor. The UAV controller 207 may befurther connected with a remote controller 208, such as a hand-held useroperated remote control device, or a ground-based navigation system.

According to various embodiments, the power supply 205 can include abattery pack 220 and a battery pack controller 227 that manages outputfrom the battery pack. The battery pack 220 includes an array of batterycells 221. The battery cells 221 are typically elongate battery cellsthat are arranged in a closely packed array with air-filled spacebetween the battery cells for exhausting heat and thermally isolatingthe battery cells from each other. According to various embodiments, thebattery cells 221 are cylindrical battery cells that are sandwichedbetween substantially planar enclosure elements. According to someembodiments, the array of battery cells 221 are lithium ion batterycells.

The battery pack 220 includes sensors 225 that are positioned adjacentthe battery cells 221 or connected with the battery cells to sensetemperature variations of the individual battery cells within thebattery pack. According to various embodiments, the sensors 225 caninclude infrared sensors that monitor an interior of the battery packfor infrared radiation indicative of temperatures above a thresholdtemperature. According to various other embodiments, the sensors 225 caninclude sensing circuits made up of thermistors that are attached togroups or subsets of the battery cells 221 in order to detect theoccurrence of thermal run-away events in the battery cells beforethermal failure has spread to the entire battery pack 220.

FIG. 3 illustrates an example system 300 for detecting thermal run-awayin the battery pack 320 of an autonomous or semiautonomous electricvehicle 301, in accordance with embodiments. The autonomous orsemi-autonomous vehicle 301 includes a power supply 305 that is operableto supply electrical power to the electric motors 303 in the drive trainof the autonomous or semiautonomous vehicle, under the control of thevehicle controller 307. According to some embodiments, the vehiclecontroller 307 may be further configured to take control of the vehicleincluding the management of acceleration and braking, steering, andnavigation. The electrical motors 303 can include any suitable electricmotor for use in delivering power to the wheels 337 of the vehicle 301via the drive train or axle 339, in order to propel the autonomous orsemi-autonomous vehicle 301, such as an AC electric motor or a DCelectric motor. The vehicle controller 307 may be further connected withthe user input/output device 312 that can take commands from an operatorof the electric or hybrid electric vehicle 301, or can relay informationfrom the control system 300 for display to the operator. The userinput/output device 312 can include any suitable display screen,keyboard, touchpad, voice recognition system or software, or othersuitable control system or feedback system.

According to various embodiments, the power supply 305 can include abattery pack 320 and a battery pack controller 327 that manages outputfrom the battery pack. The battery pack 320 includes an array of batterycells 321. The battery cells 321 are typically elongate battery cellsthat are arranged in a closely packed array with air-filled spacebetween the battery cells for exhausting heat and thermally isolatingthe battery cells from each other. According to various embodiments, thebattery cells 321 are cylindrical battery cells that are sandwichedbetween substantially planar enclosure elements. According to someembodiments, the array of battery cells 321 are lithium ion batterycells.

The battery pack 320 includes sensors 325 that are positioned adjacentthe battery cells 321 or connected with the battery cells to sensetemperature variations of the individual battery cells within thebattery pack. According to various embodiments, the sensors 325 caninclude infrared sensors that monitor an interior of the battery packfor infrared radiation indicative of temperatures above a thresholdtemperature. According to various other embodiments, the sensors 325 caninclude sensing circuits made up of thermistors that are attached togroups or subsets of the battery cells 321 in order to detect theoccurrence of thermal run-away events in the battery cells beforethermal failure has spread to the entire battery pack 320.

FIG. 4 illustrates an example of a battery control system 400 fordetecting thermal run-away in a battery pack 420 using infrared sensors425, in accordance with embodiments. The battery control system 400includes a controller 407 that manages delivery of electrical power froma power supply 405 to a load 403. The load 403 can be any suitable loaddescribed above, such as but not limited to a motor of an electricvehicle or hybrid electric vehicle, a UAV, any electrical systemassociated with an electrical vehicle, UAV, or any suitable stationarysystem that draws electrical power from a battery pack made up of anarray of battery cells.

The battery pack 420 includes an array of battery cells 421 that areclosely packed but spaced apart from each other to allow airflow betweenthe battery cells for cooling, electrical isolation, and/or thermalisolation. The array of battery cells 421 can be packed according to arectangular grid, according to a hexagonal or triangular grid, oraccording to any other suitable repeating arrangement. According to atleast some embodiments, the array of battery cells 421 are spaced apartsufficiently to provide open conduits 437 between adjacent battery cellsthat allow infrared radiation to reflect between the battery cells alongthe open channels. The battery cells 421 are secured within an enclosure423 that includes at least a top enclosure element 431 and a bottomenclosure element 433 that are connected to the array of battery cellsfrom above and below. The top enclosure element 431 and the bottomenclosure element 433 can include printed or attached circuitry 435 forelectrically connecting the battery cells 421 together and with thebattery controller 427 and the load 403. The circuitry 435 can take avariety of forms in order to create any suitable number of parallelsubsets of battery cells within the battery pack 420, any suitablenumber of series subsets of battery cells within the battery pack, orany suitable combination in order to produce a battery pack that has anappropriate voltage and capacity.

The top enclosure element 431 and the bottom enclosure element 433,together with the battery cells for 21, define open conduits 437 betweenthe battery cells. These open conduits 437 are able to reflect infraredlight emitted from individual battery cells 421 along the conduits.According to some embodiments, the battery cells 421 can include outershells, outer surface coatings, or can be formed of a material that isinfrared-reflective. Some suitable infrared reflective materialsinclude, e.g., aluminum, and various infrared reflective pigments.According to some other embodiments, interior surfaces of the topenclosure element 431 and the bottom enclosure element four and 33 mayalso or alternatively include surface coatings that are infraredreflective or can be composed of infrared reflective materials.According to various embodiments, exterior surfaces of the battery cells421, interior surfaces of the top enclosure element 431 and bottomenclosure element 433, or any suitable combination thereof, can have aninfrared reflectivity coefficient of at least 0.2.

The power supply 405 includes a battery pack 420 managed by thecontroller 407 and/or a local battery controller 427. The batterycontroller 427 can be a PCB that can monitor electrical characteristicsof the battery pack 420, including but not limited to power output fromthe battery pack, voltages or currents across the battery pack, voltagesor currents across the battery cells 421, or other parameters. Accordingto various embodiments, the battery controller 427 can also monitortemperatures within the battery pack 420 in order to rapidly identifytemperatures that exceed operational parameters of the individualbattery cells 421. For example, according to various embodiments, thebattery controller 427 is connected with one or with multiple infraredsensors 425. The infrared sensors 425 are positioned at ends of theconduits 437 and oriented toward the conduits to receive incidentinfrared radiation 424 that is emitted by the battery cells 421 adjacentto each conduit. When one of the battery cells 421 is damaged oroverheats, and particularly when one of the battery cells enters athermal run-away condition (e.g., overheated battery cell 422), theoverheated battery cell emits infrared radiation at high intensity thatis reflected along one of the conduits 437 and detected by one of theinfrared sensors 425.

According to some embodiments, infrared sensors 425 can be strategicallypositioned at adjacent conduits 437, at every other conduit, or can evenbe positioned along adjacent or orthogonal sides of the battery pack 420in order to obtain temperature data from more than one side of thebattery pack. According to some embodiments, each one of the infraredsensors 425 can be connected directly with the battery controller 427,where the infrared sensors may each connect with a respective dedicatedprocessor for receiving the temperature data, or alternatively, wherethe infrared sensors may each connect with a common processor thatcollects the temperature data from any number or from all of theinfrared sensors. According to some embodiments, the infrared sensors425 can all be connected to a common bus 426, e.g., via the use of anand-on cord, or other suitable connection.

According to some embodiments, the temperature data from each one of theinfrared sensors can be processed separately and temperature data fromeach sensor can be compared against threshold temperature data, where asignal exceeding the threshold temperature data is indicative of a hightemperature along one of the conduits 437 indicative of a thermalrun-away condition. According to some other embodiments, the temperaturedata from each one of the infrared sensors 425 can be processedtogether, or merged, to a single data structure, and a thermal run-awaycondition can be identified from the combined temperature data when aportion of the combined temperature data exceeds a threshold intensity,or exceeds intensities of adjacent temperature data.

In some specific embodiments, the infrared sensors 425 can take the formof low resolution infrared cameras that produce highly pixelatedinfrared images or heat maps. Suitable infrared cameras or commerciallyavailable for applications such as presence sensors for lightingapplications or wildlife cameras, or other similar applications. Theseinfrared sensors 425 may generate a pixelated image with a resolution aslow as about eight pixels by eight pixels. The temperature datagenerated by the infrared sensors 425 can be can combined to form acombined image file by knitting the low resolution images generated bythe sensors, and processing the combined image file to identify pixelshaving a high intensity indicative of thermal run-away, or to identifypixels having intensities that are outliers with respect to adjacentpixels from other temperature data. These techniques can avoidgenerating false positives, as the temperature of the battery cells 421can vary depending on the load on the battery pack 420, the ambienttemperature, air flow within the battery pack 420, or potentially manyother parameters.

Whether the infrared sensors 425 each connect individually with thebattery controller 427, or whether the infrared sensors connect to acommon processor along a common bus 426, the use of infrared sensors tomonitor entire rows of battery cells 421 without requiring individualinstrumentation on the battery cells presents substantial advantages andcost savings. Due to thermal management constraints, individuallyinstrumenting all of the battery cells 421 is infeasible, as thecircuitry required to do so would inhibit the free flow of air withinthe enclosure 423. This approach would also significantly increase thecomplexity of the battery controller 427, as it would be required toaccept sensor wires from a prohibitively large number of temperaturesensors. The alternative approach, e.g. instrumenting the enclosure 423with spaced sensors, faces the technical challenge that detection ofthermal run-away events is significantly slowed by lack of directcontact with the overheating battery cell 422. In contrast, the infraredsensor-based approaches described herein provide for direct andimmediate monitoring of all or substantially all of the battery cells421 in the battery pack 420, minimize instrumentation or clutter with inthe enclosure 423, and provide several options for deficient wiring tothe battery controller and for monitoring the received temperature data,as described above.

FIG. 5 illustrates a second example of a battery control system 500 fordetecting thermal run-away using infrared sensors arranged in multipledirections, in accordance with embodiments. The battery control system500 includes a battery pack 520 shown in a top-down section view andomitting the enclosure. A network of infrared sensors 525 or positionspointing into the battery pack 520 along conduits 537, 538, betweenadjacent rows of battery cells 521. Conduits 537 and 538 intersect, andthe use of the infrared sensors 525 along intersecting conduits can beused to facilitate locating any battery cell undergoing a thermalrun-away event.

According to various embodiments, the infrared sensors 525 can beelectrically connected with the battery controller 527 for relayingtemperature data of the battery cells 521 to the battery controller. Asshown, an overheating battery cell 522 reflects infrared radiation 524along both of the conduits 537, 538, that are adjacent to theoverheating battery cell. (Note, the infrared radiation 524 will betransmitted in all directions, but the positioning of the battery cells521 in orderly rows and columns will tend to cause the infraredradiation to travel farthest along the conduits 537, 538.) Infraredsensors 525 position at each and of both conduits 537, 538 will detectthe infrared radiation 524 and relay the temperature data to the batterycontroller 527. Based on the related temperature data, the batterycontroller 527 can determine that a thermal run-away event is inprogress, and can respond by instructing the battery pack 520 enter apowered down state.

The temperature data obtained from multiple infrared sensors 525 can beused to identify and approximate location 539 of the overheating batterycell 422. Using this temperature data, the battery controller 527 canselectively power down a subset of the battery cells 521 that includesthe battery cells at the approximate location 539. According to somealternative embodiments, e.g. where infrared sensors 525 are positionedmore frequently at each adjacent conduit 537, 538, the batterycontroller 527 can use temperature data from multiple infrared sensors525 in order to positively identify the specific overheating batterycell 522, and either power down the battery pack 520, power down asubset of the battery cells that includes the overheating battery cell,or power down only the overheating battery cell. Powering down a batterycell 521 can also include disconnecting the battery cell from the array.

FIG. 6 illustrates an example battery control system 600 for detectingthermal run-away in a battery pack 620 using thermistor-based sensingcircuits 641, in accordance with embodiments. The battery control system600 includes a controller 607 that manages delivery of electrical powerfrom a power supply 605 to a load 603. The load 603 can be any suitableloan described above, such as but not limited to a motor of an electricvehicle or hybrid electric vehicle, a UAV, any electrical systemassociated with an electrical vehicle, UAV, or any suitable stationarysystem that draws electrical power from a battery pack made up of anarray of battery cells.

The battery pack 620 includes an array of battery cells 621 that areclosely packed but spaced apart from each other to allow airflow betweenthe battery cells for cooling, electrical isolation, and/or thermalisolation. The array of battery cells 621 can be packed according to arectangular grid, according to a hexagonal or triangular grid, oraccording to any other suitable repeating arrangement. The battery cells621 are secured within an enclosure 623 that includes at least a topenclosure element 631 and a bottom enclosure element 633 that areconnected to the array of battery cells from above and below. The topenclosure element 631 and the bottom enclosure element 633 can includeprinted or attached circuitry 635 for electrically connecting thebattery cells 621 together and with the battery controller 627 and theload 603. The circuitry 635 can take a variety of forms in order tocreate any suitable number of parallel subsets of battery cells withinthe battery pack 620, any suitable number of series subsets of batterycells within the battery pack, or any suitable combination in order toproduce a battery pack that has an appropriate voltage and capacity.

The power supply 605 includes a battery pack 620 managed by thecontroller 607 and/or a local battery controller 627. The batterycontroller 627 can be a PCB that can monitor electrical characteristicsof the battery pack 620, including but not limited to power output fromthe battery pack, voltages or currents across the battery pack, voltagesor currents across the battery cells 621, or other parameters. Accordingto various embodiments, the battery controller 627 can also monitortemperatures within the battery pack 620 in order to rapidly identifytemperatures that exceed operational parameters of the individualbattery cells 621. For example, according to various embodiments, thebattery controller 627 is connected with a set of temperature sensingcircuit controllers 625, each one electrically connected to a sensingcircuit 641 that extends into the enclosure 623 and is connected with asubset of the array of battery cells 621. Each one of the sensingcircuits 641 includes a series of thermistor containing nodes 643 thatcan attach to the battery cells 621. According to various embodiments,each sensing circuit 641 can connect to anywhere from one battery cell621, to 10 battery cells, to 50 battery cells, or to more than 50battery cells. According to some embodiments, each sensing circuitcontroller 625 can attach to one of the sensing circuits 641, and canrelate temperature data from the sensing circuit to the batterycontroller 627.

The temperature data obtained via the sensing circuits 641 is based onthe temperature/resistance curve of the thermistor containing nodes 643,each one of which contains a thermistor that changes in electricalconductivity depending on the temperature of the battery cell 621 towhich the thermistor containing note is attached. According to someembodiments, the thermistors can increase in conductivity withtemperature, thus decreasing an overall resistance of the sensingcircuit 641 in response to a thermal run-away events, e.g., atoverheating battery cell 622. The opposite approach can also be used,with thermistors that decrease in conductivity with temperature, suchthat an overall resistance of the sensing circuit 641 in response tothermal run-away is decreasing. In order to identify a thermal run-awayevent, the battery controller 627 can compare an electrical parameter ofthe sensing circuits 641, such as voltage, current, or resistance, witha threshold value associated with the presence of a high-temperaturethat exceeds the operating parameters of one of the battery cells 621.Alternatively, the sensing circuit controllers 625 can convert the rawsignals received by the sensing circuits 641 and translate the signalsinto temperature data indicative of an average temperature of the subsetof battery cells 621 to which the sensing circuit 641 is attached. Thebattery controller 627 can then compare the processed temperature datawith a threshold temperature in order to determine whether a thermalrun-away event has occurred.

A wide variety of specific configurations of the sensing circuits 641and sensing circuit controllers 625 can be used without deviating fromthe principles described herein. For example, FIG. 6 shows lineararrangements of the sensing circuits 641 along parallel rows of batterycells 621, however, sensing circuits can be routed through the enclosure623 according to any suitable geometry, as needed to most efficientlycontact each one of the battery cells. The sensing circuits 641 can berouted through the open space within the enclosure 623, oralternatively, the sensing circuits can be adhered to, embedded in, oreven printed on one of the top enclosure element 631, the bottomenclosure element 633, or both. The thermistor nodes 643 are shownattached along the sides of the battery cells 621, however, they can beattached at either end of the battery cells as well. As with theinfrared sensor embodiments described above, the sensing circuitcontrollers 625 can each connect directly with the battery controller627, or the thermistor circuit controllers can connect with the batterycontroller 627 via a common bus 626. According to some alternativeembodiments, a single sensing circuit 641 can loop to connect with allof the battery cells 621. According to some further alternativeembodiments, the sensing circuits 641 can connect directly with thebattery controller 627 without passing through any intervening sensingcircuit controller 625.

The use of thermistor based sensing circuits to monitor groups ofbattery cells 621 without requiring individual monitoring leads fromeach one of the battery cells presents substantial advantages and costsavings comparable to those achieved using the infrared sensorembodiments described above. The chained approach of attaching a seriesof thermistor nodes 643 to the battery cells 621 requires far fewercircuits to be added within the enclosure 623 than other approaches toindividually instrumenting the battery cells, and the sensing circuits641 can be attached or embedded in either the top enclosure element 631or the bottom enclosure element 633 to provide for minimal impact onairflow. In addition, the thermistor based approaches described hereinprovide for immediate monitoring of the battery cells 621, while alsominimizing excess wiring and data processing requirements. Dataprocessing requirements can be further reduced by implementingthermistor based sensing circuits as a mesh that connects to all of thebattery cells through one controller, as described below with referenceto FIG. 7.

FIG. 7 illustrates a second example of a battery control system 700 fordetecting thermal run-away using a thermistor based sensing mesh 745, inaccordance with embodiments. The battery control system 700 includes abattery pack 720 shown in a top-down section view and omitting theenclosure. According to various embodiments, a thermistor basedtemperature sensing mesh 745 is connected with the battery cells 721 ofthe battery pack 720. The temperature sensing mesh 745 is made up ofmultiple sensing circuits 741 that connects with groups of the batterycells 721 similar to the sensing circuits 641 described above (FIG. 6).Each one of the sensing circuits 641 is connected in parallel, andconnected with the battery controller 727, optionally via a localsensing circuit controller 725. The sensing circuits 741 include anarrangement of chained thermistor containing nodes 743, the nodes beingconnected with the battery cells 721. A rise in temperature of any oneof the battery cells 721, e.g. overheating battery cells 722, triggers achange in the conductivity of the thermistor containing node 743attached to the battery cell. This change in conductivity can be sensedby the sensing circuit controller 725 or by the battery controller 727,and indicates a thermal run-away event.

Sensing circuits 641, 741 described above with reference to FIGS. 6 and7 can take a wide variety of forms, with advantages specific to eachform of sensing circuit. A nonlimiting selection of example sensingcircuits are described below with reference to FIGS. 8-11. It will beunderstood that the battery control systems 600, 700, and other batterycontrol systems described herein, can make use of variations on thesensing circuits described herein, combinations of the sensing circuitsdescribed herein, or alternative sensing circuits based on the sameprinciples.

FIG. 8 illustrates a first example sensing system 800 including athermistor based sensing circuit 841 having thermistors 847 arranged inseries, in accordance with embodiments. The sensing circuit 841 includesa series of nodes 843 attached to battery cells 821, where each node isa thermistor 847 that is thermally coupled with a corresponding batterycell. The sensing circuit 941 can be connected via a return or ground849 to the sensing circuit controller 825. A total resistance of thesensing circuit 841 will be a function of the collective resistance ofthe thermistors 847. This sensing circuit 841 having thermistors inseries minimizes wiring and components, however it can be limited insensitivity due to the increasing collective resistance of the sensingcircuit as the number of thermistors 847 increases. These limitationscan be mitigated by utilizing nonlinear thermistors (i.e., thermistorshaving a nonlinear resistance/temperature curve). Normal variation intemperatures in a battery pack that is underload can vary from about 30°C. to about 40° C. Temperatures indicative of thermal run-awayconditions can quickly reach 100° C., or several hundred degrees C., atthe individual battery cell undergoing thermal run-away. Therefore, theimpact on a cumulative resistance of a series circuit of thermistors bythermal run-away conditions is sufficiently high that a large number ofthermistors 847, e.g., more than 10 thermistors, or more than 50thermistors, or from 10 to 50 thermistors, can be used in series in aneffective sensing circuit 841.

FIG. 9 illustrates a second example sensing system 900 including athermistor based sensing circuit 941 having thermistors 947 arranged inparallel, in accordance with embodiments. The sensing circuit 941includes a series of nodes 943 attached to battery cells 921, where eachnode is a thermistor 947 that is thermally coupled with a correspondingbattery cell. The sensing circuit 941 can be connected via a return orground 949 to the sensing circuit controller 925. The return or ground949 must parallel the main line of the sensing circuit 941, thus, thisembodiment does require additional room for routing. A total resistanceof the sensing circuit 941 is now effectively decoupled from the lengthof the sensing circuit, however the sensing circuit may be moresensitive to minor fluctuations in temperature that affect multiplebattery cells 921. These limitations can be mitigated by utilizingnonlinear thermistors (i.e., thermistors having a nonlinearresistance/temperature curve), particularly by utilizing thermistorsthat have low responsiveness within a temperature range at which thesystem ordinarily operates, and a nonlinear response above the normaltemperature range.

In either a series or in a parallel circuit, the number of thermistorsthat can be used depends on the tolerances of the thermistor circuit andthe sensitivity of the sensing circuit. According to variousembodiments, a thermistor-based sensing circuit can detect an anomaloustemperature increase of 10° C. in a thermistor circuit having up to 100thermistor elements in series or in parallel, corresponding to a 1 mVsensitivity of the sensing circuit. However, preconditions for a thermalrun-away event can include sudden temperature spikes of individualbattery cells of more than 100° C. According to other embodiments, athermistor based sensing circuit can detect an anomalous temperatureincrease of 100° C. in a thermistor circuit having up to 200 thermistorelements arranged in series or in parallel. Various embodiments ofthermistor based sensing circuits can employ up to 200 thermistorelements arranged in series or parallel, up to 100 thermistor elementsarranged in series or parallel, or up to 10 thermistor elements arrangedin series or in parallel.

FIG. 10 illustrates an example of a thermistor based sensing system 1000that includes a temperature sensing mesh 1045, in accordance withembodiments. The sensing mesh 1045 includes a first sensing circuit 1041a and a second sensing circuit 1041 b, and may further include anysuitable number of additional sensing circuits connected in parallelwith each other. Each sensing circuit 1041 includes a series of nodes1043 attached to battery cells 1021, where each node is a thermistor1047 that is thermally coupled with a corresponding battery cell. Thesensing circuits 1041 as shown include thermistors 1047 in parallelarrangements.

The sensitivity and reliability of the thermistor based sensing systemsdescribed herein can be enhanced by utilizing nonlinear diodes incombination with thermistors attached to the battery cells. For example,FIG. 11 illustrates an example of a thermistor based sensing system 1100that includes a sensing circuit 1141 having sensing nodes 1143 thatinclude thermistors 1147 in parallel with nonlinear diodes 1151, inaccordance with embodiments. Each sensing node 1143 includes a parallelarrangement of a thermistor 1147 and nonlinear diodes 1151, e.g., Zenerdiode or comparable, that exhibits nonlinear behavior in response to achange in voltage or current. In operation, when one of the batterycells 1121 undergoes a thermal run-away events, the associatedthermistor 1147 attached to that battery cell will change inconductivity. In response, a voltage across the sensing node 1143 willchange, prompting breakdown of the nonlinear diode 1151, and an abruptchange in behavior of the diode. For Zener diodes, passing the breakdownvoltage causes the diode to allow current to flow in reverse, which isdetectable by the sensing circuit controller 1125.

FIGS. 12-18 illustrate various example processes for managing electricaldevices that include battery packs with array battery cells, includingprocesses for detecting thermal run-away events. Some or all of theprocesses 1200-1800 (or any other processes described herein, orvariations, and/or combinations thereof) may also be performed under thecontrol of one or more computer systems configured with executableinstructions and may be implemented as code (e.g., executableinstructions, one or more computer programs, or one or moreapplications) executing collectively on one or more processors, byhardware or combinations thereof. Aspects of the processes 1200-1800 maybe performed, in embodiments, by a system similar to the systems 100,200, or 300 shown in FIGS. 1-3. The system may be implemented in anelectric vehicle, such as an unmanned electric vehicle (UAV), anelectric automobile, hybrid electric automobile, and electric or hybridelectric train, ship, or any other suitable electric vehicle thatutilizes a power supply including a battery pack with arrayed batterycells. The code may be stored on a computer-readable storage medium, forexample, in the form of a computer program comprising a plurality ofinstructions executable by one or more processors. The computer-readablestorage medium may be non-transitory.

FIG. 12 is a process flow diagram 1200 illustrating a method of sensingthermal run-away in a battery pack using an infrared sensor, inaccordance with embodiments. In an embodiment, the process 1200 includesgenerating, via an infrared sensor, an infrared sensor output signal inresponse to incidence on the infrared sensor of infrared radiationemitted by a battery cell of the battery pack. (Act 1201). The systemcan monitor, via a controller, the infrared sensor output signal tomonitor for one or more temperature exceedances of battery cells of thebattery pack indicative of one or more thermal run-away conditions ofthe battery cells. (Act 1203). Monitoring the battery cells can, in someembodiments, detect preconditions to a thermal run-away event, e.g.,elevated temperatures that precede thermal run-away or that indicate anelevated risk of thermal run-away occurring, before irreversible damageto the battery cells has occurred or before actual thermal run-awayconditions have occurred. If none of the temperature data indicatetemperatures exceeding the operating conditions of the battery cells,the system can iteratively monitor the temperature data. (Act 1205). Inresponse to the infrared sensor output signal being indicative of one ormore thermal run-away conditions of the battery cells, output a thermalrun-away signal indicating the occurrence of the one or more thermalrun-away conditions of the battery cells. (Act 1207).

According to some embodiments, in addition to outputting a thermalrun-away signal, the system can further instruct a controller of a loadconnected to the battery pack that thermal run-away conditions haveoccurred, including an instruction to power down the load. (Act 1209).In addition, or alternatively, the system can disconnect the batterycells of the battery pack in order to preserve battery pack function.(Act 1211).

FIG. 13 is a process flow diagram 1300 illustrating a method of sensingand locating thermal run-away in a battery pack using infrared sensors,in accordance with embodiments. In an embodiment, the process 1300includes generating, via a first infrared sensor, a first infraredsensor output signal in response to incidence on the infrared sensor ofinfrared radiation emitted by a battery cell of the battery pack. (Act1301). The process 1300 further includes generating, via a secondinfrared sensor, a second infrared sensor output signal in response toincidence on the second infrared sensor of infrared radiation emitted bythe same battery cell. (Act 1303). The system can monitor, via acontroller, the first and second infrared sensor output signals tomonitor for one or more temperature exceedances of battery cells of thebattery pack indicative of one or more thermal run-away conditions ofthe battery cells. (Act 1305). Monitoring the battery cells can, in someembodiments, detect preconditions to a thermal run-away event, e.g.,elevated temperatures that precede thermal run-away or that indicate anelevated risk of thermal run-away occurring, before irreversible damageto the battery cells has occurred or before actual thermal run-awayconditions have occurred.

If none of the temperature data indicate temperatures exceeding theoperating conditions of the battery cells, the system can iterativelymonitor the temperature data. (Act 1307). In response to either thefirst infrared sensor output signal or the second infrared sensor outputsignal being indicative of one or more thermal run-away conditions ofthe battery cells, the system can output a thermal run-away signalindicating the occurrence of the one or more thermal run-away conditionsof the battery cells. (Act 1309). The system can further determine,based on the first infrared sensor and the second infrared sensorassociated with the first and second infrared sensor output signals, alocation within the battery pack of the battery cell undergoing thermalrun-away conditions. (Act 1311). In response to determining the locationof the battery cell undergoing thermal run-away conditions, the systemcan disconnect the battery cell undergoing thermal run-away, or candisconnect a subset of the battery cells undergoing thermal run-away,without disconnecting the entire battery pack. (Act 1313).

FIG. 14 is a process flow diagram 1400 illustrating a method of sensingthermal run-away in a battery pack using a thermistor based sensingcircuit, in accordance with embodiments. In an embodiment, the process1400 includes receiving a resistance level output signal from a sensingcircuit thermally coupled with a subset of the battery cells of an arrayof battery cells in a battery pack. (Act 1401). Based on the resistancelevel output signal, the system can monitor for one or more temperatureexceedances of the battery cells indicative of one or more thermalrun-away conditions of the battery cells. (Act 1403). Monitoring thebattery cells can, in some embodiments, detect preconditions to athermal run-away event, e.g., elevated temperatures that precede thermalrun-away or that indicate an elevated risk of thermal run-awayoccurring, before irreversible damage to the battery cells has occurredor before actual thermal run-away conditions have occurred. If none ofthe temperature data indicate temperatures exceeding the operatingconditions of the battery cells, the system can iteratively monitor theresistance level output signal. (Act 1305).

In response to the resistance level output signal being indicative ofone or more thermal run-away conditions of the battery cells, the systemcan output a thermal run-away signal indicating the occurrence of theone or more thermal run-away conditions of the battery cells.

(Act 1307). According to some embodiments, in addition to outputting athermal run-away signal, the system can further instruct a controller ofa load connected to the battery pack that thermal run-away conditionshave occurred, including an instruction to power down the load. (Act1309). In addition, or alternatively, the system can disconnect thebattery cells of the battery pack in order to preserve battery packfunction. (Act 1311).

FIG. 15 is a process flow diagram 1500 illustrating a method of sensingand locating thermal run-away in a battery pack using thermistor basedsensing circuits, in accordance with embodiments. In an embodiment, theprocess 1500 includes receiving a resistance level output signal from asensing circuit thermally coupled with a subset of the battery cells ofan array of battery cells in a battery pack. (Act 1501). The process1500 further includes receiving, via a second sensing circuit thermallycoupled with a different subset of the battery cells, a secondresistance level output signal. (Act 1503). The system can monitor, viaa controller, the first and second resistance level output signals tomonitor for one or more temperature exceedances of battery cells of thebattery pack indicative of one or more thermal run-away conditions ofthe battery cells. (Act 1505). Monitoring the battery cells can, in someembodiments, detect preconditions to a thermal run-away event, e.g.,elevated temperatures that precede thermal run-away or that indicate anelevated risk of thermal run-away occurring, before irreversible damageto the battery cells has occurred or before actual thermal run-awayconditions have occurred.

If none of the temperature data indicate temperatures exceeding theoperating conditions of the battery cells, the system can iterativelymonitor the resistance level output signals. (Act 1507). In response toeither the resistance level output signal or the second resistance leveloutput signal being indicative of one or more thermal run-awayconditions of the battery cells, the system can output a thermalrun-away signal indicating the occurrence of the one or more thermalrun-away conditions of the battery cells. (Act 1509). The system canfurther determine, based on the first and second resistance level outputsignals, a location within the battery pack of the battery cellundergoing thermal run-away conditions, e.g., whether the battery packundergoing thermal runway conditions is in a first subset of the batterycells or in the second subset of the battery cells. (Act 1511). Inresponse to determining the location of the battery cell undergoingthermal run-away conditions, the system can disconnect the subset of thebattery cells containing the battery cell undergoing thermal run-away,without disconnecting the entire battery pack. (Act 1513).

FIG. 16 is a process flow diagram 1600 illustrating a method of sensingthermal run-away in a battery pack and managing power output to a load,in accordance with embodiments. In an embodiment, the process 1600includes receiving a thermal run-away signal indicative that thermalrun-away conditions or preconditions have been detected in a batterycell of a battery pack powering the load. (Act 1601). According to someembodiments, the thermal run-away signal can be generated when atemperature in a battery cell of the battery pack exceeds a thresholdtemperature, but before thermal run-away conditions are inevitable, thuspermitting the system to prevent or mitigate thermal run-away before thebattery pack is damaged. According to various other embodiments, thethreshold can be set to detect excess heat generated by a battery cellbefore thermal run-away conditions have been met, when thermal run-awayconditions are just beginning and still recoverable, or after a thermalrun-away event has occurred. In response to receiving the thermalrun-away signal, the system can reduce a power draw from the batterypack. (Act 1603). Reducing the power draw can include, according tovarious embodiments: imposing a limit in the power draw by a batterycontroller, instructing a controller of the load associated with thebattery pack to limit demand for power, or selectively disconnecting anaffected battery cell or a subset of the battery cells in order tomitigate or reverse the thermal run-away event. The system can generateinstruction to a controller of the load, e.g. a controller of anelectric vehicle, UAV, or other electronic device drawing power from thebattery pack, to initiate a safe shutdown. (Act 1605). According to someembodiments, the system can monitor the controller for a reply signalindicating that a safe shutdown has occurred, or can monitor an outputof the battery pack to determine when safe shutdown has occurred, andcan initiate a shutdown of a portion or of all of the battery pack inresponse. (Act 1607). Alternatively, or in parallel, the system can waitfor a predetermined period of time before automatically initiating ashutdown of a portion or all of the battery pack if a reply signal isnot received from the controller. (Act 1609).

FIG. 17 is a process flow diagram 1700 illustrating a method of sensingthermal run-away in a battery pack and managing safe shutdown of a UAV,in accordance with embodiments. In an embodiment, the process 1700includes receiving a thermal run-away signal indicative of a temperatureevent that can precede thermal run-away conditions in the battery packpowering a UAV that is in flight. (Act 1701). The thermal run-awaysignal can be generated when a temperature in a battery cell of thebattery pack exceeds a threshold temperature, and the threshold can beset to detect excess heat generated by a battery cell before thermalrun-away conditions have been met, or when thermal run-away conditionsare just beginning and still recoverable. In response to receiving thethermal run-away signal, the system can attempt to mitigate or preventthermal run-away by limiting the power draw from the battery pack by thesystems of the UAV (e.g., propulsive systems), either under the controlof a battery pack controller which throttles the amount of poweravailable to the UAV, or by the UAV controller. (Act 1703). The systemcan then generate instruction to a controller of the UAV drawing powerfrom the battery pack to initiate a safe shutdown, including identifyinga safe landing zone free of obstacles, safely landing the UAV, andpowering down the rotors. (Act 1705). According to some embodiments, thesystem can monitor the controller for a reply signal indicating that asafe shutdown has occurred, or can monitor an output of the battery packto determine when safe shutdown has occurred, and can initiate ashutdown of a portion or of all of the battery pack in response. (Act1707). Although it is possible to also initiate an automatic shutdown ofthe battery pack in response to thermal run-away, in the context of aUAV, it is often preferable to continue seeking a safe landing zonebefore powering down the battery pack, even if doing so might damage thebattery pack. However, the intervening step of reducing power draw fromthe UAV battery pack can, in some cases, reverse or slow the onset ofthermal run-away conditions such that the UAV can safely land andsubsequently disconnect the battery cells, thus halting or preventingthermal run-away.

FIG. 18 is a process flow diagram 1800 illustrating a method of sensingthermal run-away in a battery pack and managing safe shutdown of anautonomous or semiautonomous vehicle, in accordance with embodiments. Inan embodiment, the process 1800 includes receiving a thermal run-awaysignal indicative of preconditions for a thermal run-away event, e.g.,when a temperature in a battery cell of the battery pack exceeds athreshold temperature, for a battery pack powering an autonomous orsemiautonomous electric or hybrid electric vehicle. (Act 1801). Thethreshold can be set to detect excess heat generated by a battery cellbefore thermal run-away conditions have been met, when thermal run-awayconditions are just beginning and still recoverable, or when thermalrun-away conditions are detected. As an initial response, the system caninstruct either a controller of the battery pack, or a controller of thevehicle, to limit a power draw from the battery pack in order to delayor prevent a thermal run-away event from occurring. (Act 1803). Thisresponse can include, in some cases, limiting an amount of a power drawfrom the battery pack as a whole. In some other cases, the response caninclude disconnecting portions of the battery pack, e.g., a battery cellor a subset of the battery cells affected by the thermal run-awayconditions. In response to receiving the thermal run-away signal, thesystem can also generate instructions for a controller of the vehicledrawing power from the battery pack to initiate a safe shutdown,including identifying a safe location to park, slowing the vehicle, andbringing the vehicle safely to rest. (Act 1805). According to someembodiments, the system can monitor the controller for a reply signalindicating that a safe shutdown has occurred, or can monitor and outputof the battery pack to determine when safe shutdown has occurred, andcan initiate a shutdown of a portion or of all of the battery pack inresponse. (Act 1807). Alternatively, or in parallel, the system can waitfor a predetermined period of time before automatically initiating ashutdown of a portion or all of the battery pack if a reply signal isnot received from the controller. (Act 1809).

The specification and drawings are to be regarded in an illustrativerather than a restrictive sense. It will, however, be evident thatvarious modifications and changes may be made thereunto withoutdeparting from the broader spirit and scope of the disclosure as setforth in the claims.

Other variations are within the spirit of the present disclosure. Thus,while the disclosed techniques are susceptible to various modificationsand alternative constructions, certain illustrated embodiments thereofare shown in the drawings and have been described above in detail. Itshould be understood, however, that there is no intention to limit thedisclosure to the specific form or forms disclosed, but on the contrary,the intention is to cover all modifications, alternative constructions,and equivalents falling within the spirit and scope of the disclosure,as defined in the appended claims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the disclosed embodiments (especially in thecontext of the following claims) are to be construed to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The terms “comprising,” “having,” “including,”and “containing” are to be construed as open-ended terms (i.e., meaning“including, but not limited to,”) unless otherwise noted. The term“connected” is to be construed as partly or wholly contained within,attached to, or joined together, even if there is something intervening.Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate embodiments of the disclosure anddoes not pose a limitation on the scope of the disclosure unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe disclosure.

Disjunctive language such as the phrase “at least one of X, Y, or Z,”unless specifically stated otherwise, is intended to be understoodwithin the context as used in general to present that an item, term,etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y,and/or Z). Thus, such disjunctive language is not generally intended to,and should not, imply that certain embodiments require at least one ofX, at least one of Y, or at least one of Z to each be present.

Preferred embodiments of this disclosure are described herein, includingthe best mode known to the inventors for carrying out the disclosure.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate and the inventors intend for the disclosure to be practicedotherwise than as specifically described herein. Accordingly, thisdisclosure includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the disclosure unlessotherwise indicated herein or otherwise clearly contradicted by context.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

What is claimed is:
 1. A battery system, comprising: a battery packcomprising an array of battery cells; a load that is electricallyconnected with the battery pack and configured to draw power from thearray battery cells; an infrared sensor configured to generate a firstinfrared sensor output signal in response to incidence on the infraredsensor of infrared radiation emitted by at least two of the batterycells; and a controller comprising at least one processor and a memorydevice containing executable instructions that, when executed by the atleast one processor, cause the controller to: receive and monitor theinfrared sensor output signal to monitor for one or more temperatureexceedances of the battery cells indicative of one or more thermalrun-away conditions of the battery cells; and in response to theinfrared sensor output signal being indicative of one or more thermalrun-away conditions of the battery cells, output a thermal run-awaysignal indicating the occurrence of the one or more thermal run-awayconditions of the battery cells.
 2. The system of claim 1, wherein: theload comprises one of: an electric motor for an unmanned aerial vehicle,an electric vehicle, or a hybrid vehicle; and generating the signalcomprises generating a warning for presentation to a user indicativethat the battery pack has entered thermal run-away.
 3. The system ofclaim 1, wherein: the load comprises one of: an electric motor for anunmanned aerial vehicle, an electric vehicle, or a hybrid vehicle; andgenerating the signal comprises instructing the electric motor to reducea power consumption or to halt a power consumption from the batterypack.
 4. The system of claim 1, further comprising a second infraredsensor arranged to sense infrared radiation emitted or reflected by atleast two of the battery cells, wherein the executable instructions,when executed by the at least one processor, further cause thecontroller to: receive and monitor the first infrared sensor outputsignal generated by the first infrared sensor and a second infraredsensor output signal generated by the second infrared sensor to monitorfor one or more temperature exceedances of the battery cells indicativeof one or more thermal run-away conditions of the battery cells; andidentify a location of a battery cell at which the one or more thermalrun-away conditions have occurred based on the first infrared sensoroutput signal and the second infrared sensor output signal.
 5. A methodof detecting a thermal run-away condition of a battery pack, the methodcomprising: generating, via an infrared sensor, a first infrared sensoroutput signal in response to incidence on the one or more infraredsensors of infrared radiation emitted by at least one battery cell of anarray of battery cells of the battery pack; monitoring, via acontroller, the infrared sensor output signal to monitor for one or moretemperature exceedances of battery cells of the battery pack, the one ormore temperature exceedances being indicative of one or more thermalrun-away conditions of the battery cells; and in response to theinfrared sensor output signal being indicative of one or more thermalrun-away conditions of the battery cells, output a thermal run-awaysignal indicating the occurrence of the one or more thermal run-awayconditions of the battery cells.
 6. The method of claim 5, wherein thebattery pack is electrically connected with an electric motor of anelectric vehicle, the method further comprising: in response to theinfrared sensor output signal being indicative of the one or moretemperature exceedances of the battery cells, instructing the motor ofthe electric vehicle to enter a low-power state or to power down.
 7. Themethod of claim 5, wherein the battery pack is electrically connectedwith an electric motor of an unmanned aerial vehicle (UAV), the methodfurther comprising: in response to the infrared sensor output signalbeing indicative of the one or more temperature exceedances of thebattery cells, instructing a controller of the UAV to initiate acontrolled landing.
 8. The method of claim 5, wherein the battery packis electrically connected with an electric motor of an autonomous orsemi-autonomous automobile, the method further comprising: in responseto the infrared sensor output signal being indicative of the one or moretemperature exceedances of the battery cells, instructing a controllerof the autonomous or semi-autonomous automobile to initiate a controlledstop.
 9. The method of claim 5, further comprising: generating a secondinfrared sensor output signal, via a second infrared sensor, in responseto incidence of infrared radiation on the second infrared sensor;determining a location of the battery cell associated with the one ormore temperature exceedances based on the first infrared sensor outputsignal and second infrared sensor output signal.
 10. The method of claim5, further comprising: generating a second infrared sensor outputsignal, via a second infrared sensor, in response to incidence ofinfrared radiation on the second infrared sensor; relaying the infraredsensor output signal and the second infrared sensor output signal to acommon processor via a common bus.
 11. The method of claim 5, furthercomprising: generating a second infrared sensor output signal, via asecond infrared sensor, in response to incidence of infrared radiationon the second infrared sensor; generating a first thermal image from theinfrared sensor output signal and a second thermal image from the secondinfrared sensor output signal; assembling a composite thermal image bycombining the respective first and second thermal images; and detectingthe one or more temperature exceedances of the battery cells indicativeof thermal run-away by identifying an irregularity in the compositethermal image.
 12. The method of claim 11, further comprising:determining a location of the battery cell at which the one or moretemperature exceedances is detected based on a position of theirregularity in the composite thermal image.
 13. A power supply device,comprising: a battery pack comprising: an enclosure comprising top andbottom elements comprising a plurality of electrical connection points;and an array of battery cells contained within the enclosure, thebattery cells being connected with the top and bottom elements andelectrically connected with the plurality of electrical connectionpoints, the battery cells being spaced apart from each other, and eachone of the battery cells being connected with the top element of theenclosure at a first end and with the bottom element of the enclosure ata second end; one or more infrared sensors connected with the enclosureand configured to generate an infrared sensor output signal in responseto incidence on the one or more infrared sensors of infrared radiation;and a controller comprising a processor and a memory device containingexecutable instructions that, when executed by the processor, cause thecontroller to: receive the infrared sensor output signal from the one ormore infrared sensors; and detect that a thermal run-away event hasoccurred in the battery pack based on the received infrared sensoroutput signal indicating that a temperature of an individual batterycell exceeds a threshold temperature.
 14. The device of claim 13,wherein: the thermal run-away event comprises a temperature exceedancethat precedes thermal run-away; and the executable instructions, whenexecuted by the processor, further cause the controller to reduce apower output of the battery pack to mitigate or reverse the thermalrun-away event.
 15. The device of claim 13, wherein at least one of afirst interior surface of the top element of the enclosure, a secondinterior surface of the bottom element of the enclosure, or an outershell of each one of the battery cells comprises a material having aninfrared reflectivity of at least 0.2.
 16. The device of claim 13,wherein the one or more infrared sensors generate the infrared sensoroutput signal in the form of image data comprising pixels, an intensityof each one of the pixels being indicative of an amount of infraredradiation collected by the one or more infrared sensors.
 17. The deviceof claim 13, wherein: the array of battery cells comprises first rows ofbattery cells aligned in a first direction and separated by a firstchannel between the battery cells; and a first infrared sensor of theone or more infrared sensors is positioned at an end of the firstchannel and oriented to detect infrared radiation emitted and reflectedby a subset of the battery cells adjacent to the first channel.
 18. Thedevice of claim 17, wherein: the array of battery cells furthercomprises second rows of battery cells aligned in a second directionthat intersects with the first rows of battery cells, the second rows ofbattery cells separated by a second channel between the battery cellsthat intersects with the first channel; a second infrared sensor of theone or more infrared sensors is positioned at a second end of the secondchannel and oriented to detect infrared radiation emitted and reflectedby a second subset of the battery cells adjacent to the second channel;and the controller is further configured to identify, based on a firstinfrared sensor output signal generated by the first infrared sensor anda second infrared sensor output signal generated by the second infraredsensor, a position of a battery cell at which the one or moretemperature exceedances as occurred.
 19. The device of claim 13,wherein: the array of battery cells comprises a closely packed hexagonalgrid of the battery cells; and the one or more infrared sensors arepositioned at respective ends of a plurality of rows and columns of thebattery cells in the array of battery cells, and oriented to detectinfrared radiation emitted and reflected by subsets of the battery cellsadjacent the respective rows and columns at which the one or moreinfrared sensors are positioned.
 20. The device of claim 13, wherein thebattery pack is electrically connected to power an electric motor of oneof an unmanned aerial vehicle (UAV), electric vehicle (EV), or hybridelectric vehicle (HEV).